DNA & Behavior: Is Our Fate in Our Genes?

Human traits, especially involving behavior, are likely to have a complex genetic basis incorporating many genetic and environmental influences. Learn about the field of behavioral genetics and explore whether you carry some of your fate in your genes.

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What do attached ear lobes, blue eyes, and tongue-rolling have in common? They are traits determined by your genes. But many researchers also believe that genes influence alcoholism, homosexuality, and a predisposition for anxiety. In DNA and Behavior: Is Our Fate In Our Genes?, The DNA Files looked at DNA and its possible influence on our behavior.

Research on psychology and behavior is increasingly incorporating genomic studies. In July 2007, Oxford University researchers announced the discovery of a gene that appears to increase the odds of being left-handed. In right-handed people, the left side of the brain usually controls speech and language, and the right side controls emotions. In left-handed people, the opposite is often true, and researchers believe the LRRTM1 gene is responsible for this flip. While knowing you have a predisposition to being left-handed might be interesting, it pales in importance to knowing you have a predisposition to a disabling psychiatric disorder. As of 2007, the Online Mendelian Inheritance in Man (OMIM) database lists 2,147 observable traits with a known molecular basis, including Down syndrome, schizophrenia, and many forms of panic disorders. Ongoing research at UCSF aims to identify and understand the genetic basis of panic and anxiety-related disorders by using dogs as a model. Many breeds of dog exhibit the panic and anxiety behaviors that humans do, including noise phobia and obsessive-compulsive disorders. According to UCSF geneticist and psychiatrist Steven Hamilton, "If we find a gene or set of genes that are associated with panic-like disorders in the dog, we can go back and look more closely in our samples from human families at the human forms of those genes."

In 2005, National Institutes of Health researcher Dean Hamer identified three chromosomal regions that he said linked to sexual orientation. This finding, along with his earlier claims of a "gay gene," was very controversial among scientists. So far, no other studies have replicated his findings. Hamer also recently pointed to the existence of a "God gene" for religious experience in his book The God Gene: How Faith Is Hardwired into Our Genes. Hamer suggests that human spirituality is an inherited trait, and he says he has located one of the genes responsible. This gene codes for various neurotransmitters that influence our moods. Although he is now focusing on new therapeutics for HIV/AIDS, Hamer continues to research the genetic basis of homosexuality.

While the idea that researchers can find a single gene for a specific behavioral trait makes for an exciting news story or a sensational movie, it simply isn't true. Human traits, especially involving behavior, are likely to have a complex genetic basis incorporating many genetic and environmental influences.
Original Program Description, 1998

What if you had a tendency to over-indulge in alcohol from time to time? And what if you found out that you had a genetic predisposition for addictive behavior? Would this knowledge inspire you to curb your drinking? Or would you feel resigned to your "fate" and drink all the more as a result? It's a question worth pondering as scientists further study possible genetic influences on behavior.

This program describes key studies that attempt to explain specific behaviors. For example, you'll learn about twin studies conducted to determine whether there is a genetic influence on homosexuality. Some scientists hope that establishing a genetic basis for homosexuality will help foster greater acceptance of homosexuals. Opponents of the research fear that instead, there may be renewed efforts to "cure" them. You'll hear first-hand views from scientists and subjects of the study, and then you can draw your own conclusions.

You'll also find out about a less-publicized but much-studied behavior: novelty seeking. What drives some people continually to seek out new experiences - sometimes with dangerous consequences? And how do scientists define such behaviors cross-culturally? What constitutes novelty seeking in Manhattan? In Papua New Guinea?

In addition, the program examines genetic research conducted on mice that aims to shed new light on addictive personalities. Tour one "mouse behavior" lab and learn about the latest findings on alcoholic traits. What does it mean to have a "predisposition" for an addictive behavior? If there is a genetic basis for alcoholism, how would this affect the way alcoholism is treated?

By exploring these three behaviors — homosexuality, novelty seeking, and addiction - we examine how the field of behavioral genetics may affect each of us individually and impact society as a whole.